1. Field of the Invention
This invention relates to a parts feeding apparatus for successively feeding parts from a parts collection drum to the next station, and more particularly to a parts feeder suitable for various kinds of parts having a unique cross-sectional shape and a directivity and for feeding such parts in correct posture.
2. Description of the Related Art
Conventionally, in manufacturing articles, such as slide fasteners, each comprising a plurality of parts of different shapes, the individual parts are fed successively, in the order of attaching, to a parts attaching station where the individual parts are attached to a fastener chain at a predetermined position in the same posture. For this purpose, as disclosed in, for example, Japanese Patent Laid-Open Publication No. Hei 5-178447, a so-called bowl-type parts feeder is generally used which comprises a bottomed vibrating bowl, with a spiral parts guide along an inside wall surface, and a chute in the form of a plate extending between an outlet of the spiral parts guide in the bowl and the parts attaching station.
A drum-type parts feeder for slide fastener sliders is disclosed in, for example, U.S. Pat. No. 3,116,544. The parts feeder comprises a horizontal drum to be driven for one-way rotation about a substantially horizontal axis, a rotary screw shaft extending from inside of the horizontal drum to outside of the drum along the drum axis, and a chute in the form of a plate disposed adjacent to the circumferential surface of the rotary screw shaft and extending outwardly from the drum in parallel to the drum axis. The horizontal drum has on its inside wall surface a plurality of plates extending radially inwardly and spaced from one another at a predetermined phase angle. Many parts accumulated in the horizontal drum are scooped by the radial plates in response to rotation of the horizontal drum and, when the individual wing comes to a position diagonally upwardly of the drum, the parts drop from the wing via a gutter and are caught and received by the upper edge of the chute.
Subsequently, the parts are fed on and along the chute outwardly of the drum in response to the turn of the rotary screw shaft. During that time, if the individual parts supported on the chute are out of predetermined posture, a pin projecting radially from the outlet-side end of the rotary screw shaft hits one end of a lever, which is mounted at the outlet of the chute, at every rotation of the rotary screw shaft to pivotally move the other end of the lever upwardly, thereby removing the out-of-predetermined-posture parts from the chute.
However, in the bowl-type parts feeder disclosed in Japanese Patent Laid-Open Publication No. Hei 5-178447, since the feeding of parts depends on circumferential vibration of-the bowl, it is not only difficult to transfer the parts smoothly to the spiral guide but not easy to advance the parts smoothly on the guide, thus causing only a limited increase of parts feeding speed. Also there is no guarantee that the parts are reliably transferred from the spiral guide to the plate-like chute.
In the drum-type parts feeder disclosed in U.S. Pat. No. 3,116,544, since the parts feed speed depends on the rotation of the rotary screw shaft, it is theoretically possible to increase the parts feed speed by increasing the number of rotations of the screw shaft. However, the parts tend to drop from the chute due to their shape during feeding, and the individual parts once ridden on the chute cannot advance by itself unless succeeding parts are fed. Further, since there is no means for removing any parts remaining not advanced on the chute during feeding, it would be inevitable to stop operating the whole machine if such stagnation of parts occurs, thus causing only a limited rate of production.